1. Field of the Invention
The present invention relates to a propylene resin composition and a stretched film produced therefrom. More particular, the present invention relates to a propylene resin composition that can provide a stretched film which possesses excellent transparency, gloss, and blocking resistance without sacrificing low temperature shrinkability and, in addition, exhibits excellent hot slip properties at the time of packaging and pinhole resistance at the time of shrink packaging after melt cutting and sealing, causes no significant lowering in transparency and gloss upon shrinking, and is free from separation of an anti-blocking agent at the time of formation, slitting or the like of the film.
2. Background Art
Polypropylene films have been widely used as biaxially shrinkable shrink films in packaging of containers for instant foods, such as instant noodles, packed liquors and the like. They, however, have not always satisfied requirements for properties, such as blocking resistance, scratch resistance, hot slip properties at the time of packaging, pinhole resistance at the time of shrink packaging, and transparency and gloss after shrinking.
For example, in order to prepare films possessing excellent low temperature shrinkability, a method has been proposed wherein the ethylene content of a propylene/ethylene random copolymer is increased to lower the melting peak temperature, thereby improving the low temperature shrinkability. This method, wherein the ethylene content is increased, however, suffers from problems associated with blocking resistance, scratch resistance, hot slip properties at the time of packaging (slip properties in the step of tucking a film on a tube by means of a shrink packaging machine to package a container (wherein heating with a heater for melt cutting and sealing is carried out) or slipperiness between containers which have been shrink packaged, in the step of packing in a box, after passage through a shrink tunnel), pinhole resistance at the time of shrink packaging after melt cutting and sealing, transparency after shrinking, or lowered gloss.
Even though these quality requirements could have been satisfied, problems remain unsolved such as separation of an anti-blocking agent during formation of films which causes deposition of powder of the anti-blocking agent onto a roller or occurrence of powder at the time of slitting or bag making.
Accordingly, it is an object of the present invention to provide a propylene resin composition that can provide a stretched film which possesses excellent transparency, gloss, blocking resistance, and scratch resistance without sacrificing low temperature shrinkability and, in addition, exhibits excellent hot slip properties at the time of packaging and pinhole resistance at the time of shrink packaging after melt cutting and sealing, causes no significant lowering in transparency and gloss upon shrinking, and is free from separation of an anti-blocking agent at the time of formation, slitting or the like of the film.